HONOLULU -- The second of the city's two ferry boats began service on Wednesday.

The Rachel Marie had engine trouble on Monday morning when it was supposed to join another ferry on three round trips between Kalaeloa and Honolulu Harbor.

A new master control unit for one of the ferry's two engines was flown in from Detroit, city officials said. The city installed the unit on Tuesday night.

The city is offering free fares all this week, trying to get commuters to try out the hour-long ferry rides to and from town.